Genome of alkaliphilic Bacillus pseudofirmus OF4 reveals adaptations that support the ability to grow in an external pH range from 7.5 to 11.4
Article first published online: 27 SEP 2011
© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd
Thematic Issue: Human Microbiome
Volume 13, Issue 12, pages 3289–3309, December 2011
How to Cite
Janto, B., Ahmed, A., Ito, M., Liu, J., Hicks, D. B., Pagni, S., Fackelmayer, O. J., Smith, T.-A., Earl, J., Elbourne, L. D.H., Hassan, K., Paulsen, I. T., Kolstø, A.-B., Tourasse, N. J., Ehrlich, G. D., Boissy, R., Ivey, D. M., Li, G., Xue, Y., Ma, Y., Hu, F. Z. and Krulwich, T. A. (2011), Genome of alkaliphilic Bacillus pseudofirmus OF4 reveals adaptations that support the ability to grow in an external pH range from 7.5 to 11.4. Environmental Microbiology, 13: 3289–3309. doi: 10.1111/j.1462-2920.2011.02591.x
- Issue published online: 30 NOV 2011
- Article first published online: 27 SEP 2011
- Received 7 July, 2011; revised 11 August, 2011; accepted 11 August, 2011.
Bacillus pseudofirmus OF4 is an extreme but facultative alkaliphile that grows non-fermentatively in a pH range from 7.5 to above 11.4 and can withstand large sudden increases in external pH. It is a model organism for studies of bioenergetics at high pH, at which energy demands are higher than at neutral pH because both cytoplasmic pH homeostasis and ATP synthesis require more energy. The alkaliphile also tolerates a cytoplasmic pH > 9.0 at external pH values at which the pH homeostasis capacity is exceeded, and manages other stresses that are exacerbated at alkaline pH, e.g. sodium, oxidative and cell wall stresses. The genome of B. pseudofirmus OF4 includes two plasmids that are lost from some mutants without viability loss. The plasmids may provide a reservoir of mobile elements that promote adaptive chromosomal rearrangements under particular environmental conditions. The genome also reveals a more acidic pI profile for proteins exposed on the outer surface than found in neutralophiles. A large array of transporters and regulatory genes are predicted to protect the alkaliphile from its overlapping stresses. In addition, unanticipated metabolic versatility was observed, which could ensure requisite energy for alkaliphily under diverse conditions.